High capacity mass transfer plate for columns



United States Patent [72] inventors KlausHoppe;

Gerhard Krueger, Magdeburg, Germany [21] AppLNo. 780,069 1 [22] FiledNov.29,'l968 [45] Patented Dec. 29,1970 [73] Assignee Veb GermaniaChemieanlagen-Und Apparatebau [54] HIGH CAPACITY MASS TRANSFER PLATE FORCOLUMNS 7 Claims, 4 Drawing Figs.

[52] U.S.Cl 261/114, 34/57,34/171 [51] Int.Cl B01d3/16 [50]Fieldoi'Search ..26l/ll4(J.P.); 34/57T,l7l

[ 56] References Cited UNITED STATES PATENTS 2,737,377 3/1956Hugginsetal. 26l/ll4(j.p.) 2,784,953 3/1957 N 261/ll4(j.p.) 3,062,51711/1962 Voetteretal... 261/ll4(j.p.) 3,156,746 ll/l964 Kittel26l/1l4(j.p.)

FOREIGN PATENTS 744,906 2/1956 GreatBritain 26l/ll4(j.p.)

Primary Examiner-Jim R. Miles Attorney-Nolte and Nolte ABSTRACT: In acolumn for contact oifa liquid or a fluidized particulate solid with agas or vapor in which the column is upright and the gas or vapor isdirected in a net upward direction through the column, a substantiallyhorizontal plate extending substantially across the internal diameter ofthe column, means for causing flow of the liquid or fluidizedparticulate solid across the plate, the plate being provided withopenings for passage of the gas or vapor therethrough, the openingsbeing upwardly inclined at acute angles relative both to the plane ofthe plate and in the plane of the plate to the net direction of flow(mainstream direction) of the liquid or the solid across the plate, andthe plate having at least three zones extending across the platetransversely to the net direction of flow, the zones each beingcharacterized by the acute angle in the plane of the plate between theopenings contained therein and the net flow direction being differentfrom the corresponding angle of the openings contained in the zone orzones contiguous therewith.

*H MAINSTREAM DIRECTION PAH? NIH m2 81%? FIG.3Y

MAINSTREAM DIRECTION R M SP R0DH OHK T N D i E R V NAH 1 LR N A E m R TT C S E I R A D ATTDRNEY'S HIGH CAPACITY MASS TRANSFER PLATE FOR COLUMNSThis invention relates to a high capacity exchange or mass transferplate for columns, particularly columns for various materials separationprocesses, such as, for example, absorption, desorption, distillation,rectification, extraction, washing and adsorption and for direct heatexchange.

In industry, crosscurrent plates of various constructions are known. Onetype of the these known crosscurrent plates is the so-called jet plate.There are various constructions possible for such plates which utilizethe jet principle, i.e., operation similar to the principle of a jet,for example by flaps stamped out from the sheet metal of the plate,obliquely arranged sheet metal flanges on the sheet metal of the plate,specially slit plates (so-called turbogrid plates with oblique slits),andthe like. i 7

Jet plates have the disadvantage that the stream conditions resultingfrom the strong jet effect are not especially favorable for two phasecontact, whereby there is substantial risk of the fluid fed transverselyof the plate simply blasting through the fluid bed along the plate.Furthermore, these constructions result in a very short residence timeofthefluid on the plates.

, Consequently, the contact time between the flowing phases is veryshort; Furthermore, the cross-stream plates in the case of liquid beingfed along the plate and gas being fed transversely of the plate tend tocause the liquid to spray about the plate without contact therewith. Theabove mentioned extremely short residence time and the limitation ofcontact between the materials and the plates due to droplet and sprayformation leads to a very limited separation effect. In recent times,there has become known a type of plate, which likewise works on the jetprinciple, which is known as a lamellar plate. It is constituted ofinclined, overlapping sheet metal strips which assure a specific slitopening. The lamellar plates operate hydraulically in the so-called dropregime, i.e., it does not cause the formation of cohering gas or vaporand liquid layers on the exchange plate but, rather, by virtue of thestrong jet effect, the liquid is sprayed about the plate in drop form.This leads to a very short residence time of the liquid on the plate andto very short contact times between the gas or vapor and the liquid and,accordingly, to a low separation effect for the plate. Y

Under the name Scheinmann plate" a further type of plate,

which works according to the crosscurrent principle, is

known. This plate is constituted of a rolled metal sheet whichconstitutes the entire surface of the plate and which is provided withslits uniformly oriented in the direction of the outflow. Over the plateare stream breakers which are constituted of rolled metal with largerslitsnhan the aforementioned slits and which are arranged somewhatinclined against the stream direction.

By the use of stream breakers, the disadvantages of plates which operateaccording to the jet principle are indeed lessened. However, even withthis type of plate the stream conditions are not sufficiently improved,because by high charging at the base of the plate, namely at thatportion in which the gas or vapor throughput openings oriented towardthe outlet are provided, the above referred to disadvantages stillexist.

According to the present invention, there is provided a high capacityexchange plate which provides favorable conditions for material exchange'at higher charges and, thereby, notably decreases disadvantages ofplates which operate according to the jet principle. More specifically,according to the invention, the plate is so shaped that there isprovided an orientation of gas or vapor throughput openings such that anincrease in separation effect is assured.

The plate, according to the invention, isconstructed according to thecross-stream principle and in the direction 1 across the mainstream ofthe fluid to becontacted with the gas or vapor, is divided into at leastthree segments. The throughput openings of the individual segments aresoarranged that the orientation! of the throughput openings is in theplane of the plate at an acute angle to the direction of the mainstreamof the fluidized solid or the liquid, which is fed along the plate, andthis angle varies from segment to segment. The mainstream" is the netflow and the direction of the mainstream is, accordingly, the netdirection of flow. Preferably, the sense of the aforementioned anglechanges from zone to zone. The operation of the plate,'according to theinvention, is most favorable if the plate is constituted of expandedmetal. The aforementioned angle is preferably in the range of from 30 to60. The angle between the orientation of the openings and the plane ofthe plate is preferably from 10 to 60. Above the plate and across themainstream direction, one or more known stream breakers and a likewisealready known inlet weir may be arranged.

The lengthening of the stream path of the liquid or solid and thetherewith-occuring swirling of phases and'the avoidance of the risk of ablasting through of the gas or vapor are all effected by the plate ofthe invention, which also assures an intensification of contactbetweenthe phases as compared with basic cross-stream plates and thereby causesimprovement in the separation effect. The disadvantageous carryover ofliquid or solid from plate to plate as well as to the outlet passage iseliminated by the plates according to the invention. The improvement inthe separation effect leads to a requirement for a lesser effectiveplate number for a column for a given exchange process. Moreover, thehigher capacity of the exchange plates according to the invention makespossible a decrease in the necessary plate diameter. 7 g

The invention will now be further described by reference to thedrawings, in which:

FIG. 1 is a vertical cross section view through a section of a columnincluding a plate according to the invention;

FIG. 2 is a schematic plan view ofthe plate shown in FIG. 1;

FIG. 3 is an enlargement ofa portion of theplate as shown in FIG. 1; andI FIG. 4 is an enlargement of a portion of FIG; 2.

A liquid flows over an inlet weir 7 (FlGjl) and across the plate 1 inthe net direction designated mainstreamdirection in FIGS. 2 and 4. Gasthroughput openings 3 (FIG. 3) in the plate 1 are inclined at an angle 5from the plane of the plate of 30. This angle may remain the same alongthe entire plate. However, with respect to the angle 4 in the plane ofthe plate between the openings 3 and the mainstream direction, the plateis divided into four sections. As schematically illustrated in FIGS. 2and 4, the angle 4 between the direction of the openings as projected onthe plane of the plate and the mainstream direction varies from 45 toone side of the'mainstream direction (i.e., in one sense) to 45 to theother side of the mainstream direction (i.e., in the opposite sense) andby these variations the plate is divided into four sections or zones.While the overall direction of the liquid, i.e., the mainstreamdirection, is as indicated, the force of the gas or vapor flowingobliquely upwardly through the openings 3 causes the liquid locally toundergo direction changes from zone to zone whereby the path of theliquid across the plate 1 and consequently the residence time of theliquid on the plate are lengthened. Moreover, by virtue of the repeateddirection changes, swirling of the liquid is produced and the turbulencethereof is increased whereby an additional generation of contactsurfaces is attained.

Stream breakers 6 (FIG. 1) may be provided to furtherdecrease themainstream velocity of the fluid across the plateand to decreaseentrainment.

\ While the invention is described by reference to a specific embodimentthereof, it is to be understood that the invention is not to beconsidered thereby limited but rather the scope thereof is to bedetermined by reference to the appended claims.

We claim: t

1. In a column forcontact of a-liquid or a fluidized particulate solidwith a gas or vapor in which the column is upright and the'gas or vaporis directed in a net upward direction through the column, asubstantially horizontal plate extending substantially across theinternal diameter of the column,

ineans for causing net flow of said liquid or fluidized particulatesolid substantially diametrically across the plate, said plate beingprovided with openings for passage of the gas or vapor therethrough,said openings being upwardly inclined at acute angles relative both tothe plane of the plate and in the plane of the plate, in the directionof their upward inclination, to the net direction of flow of the liquidor the solid across the plate, and said plate having at least threezones extending across the plate substantially perpendicularly to saidnet direction of flow, said zones each being characterized by said acuteangle in the plane of the plate between the openings contained thereinand the net flow direction being different from the corresponding angleof the openings contained in the zone or zones contiguous therewith.

2. In a column according to claim 1, in which said acute angle betweenthe openings and the plane of the plate is from to 60.

3. In a column according to claim 2, in which said acute angle in theplane of the plate between the openings in each of the zones and the netflow direction is from 30 to 60.

4. In a column according to claim 3, in which in the plane of the platethe inclination of the openings to the net flow direction in each zoneis in a sense oppositeto the sense of the inclination in the zone orzones contiguous therewith.

5. In a column according to claim 1, -in which said plate is constitutedofexpanded metal. p

6. In a column according to claim 1, in-which said means for causingflow of said liquid or fluidized solid: comprises a weir extending abovethe plate.

7. in a column according to claim 6, further comprising stream breakermeans positioned to disturb the flow across the plate.

